1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to transmitting and receiving data in a wireless network system, and, more particularly, to a wireless network system, in which a transmitting station sets priorities among a plurality of data to be transmitted and a receiving station processes the plurality of data according to the priorities.
2. Description of the Related Art
FIG. 1 is a view illustrating the structure of a related art superframe. As illustrated in FIG. 1, the related art superframe 100 is composed of a beacon period 110 appearing in the starting portion thereof, a Contention Access Period (CAP) 120, and Channel Time Allocation Period (CTAP) 130. During the CAP 120, asynchronous data, control commands, or the like can be transmitted or received. The CTAP 130 consists of a plurality of blocks of Management Channel Time Allocation (MCTA) 131 and a plurality of blocks of Channel Time Allocation (CTA) 132. Control commands, isochronous data, asynchronous, or the like can be transmitted or received through the CTA 132.
The length of the CAP 120 is determined by an Access Point (AP), and transmitted to stations participating in a network through a beacon frame distributed in the beacon period 110.
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is used in the CAP 120 for media access. In contrast, Time Division Multiple Access (TDMA) during which each wireless network station has a specific time window is used in the CTAP 130. An AP allocates a channel time to a device requesting media access, and performs transmission or reception of data with a corresponding wireless network station during the allocated channel time. Here, the MCTA 131 is assigned to a pair of wireless network stations attempting to exchange data, so that it performs media access through a TDMA media access, or is used as a shared CTA using the slotted Aloha protocol.
There are two data transmission schemes: a compressed data transmission mode; and an uncompressed data transmission scheme. In the first transmission mode, compressed data is transmitted through a bandwidth of several gigabytes. In the latter transmission mode, uncompressed data is transmitted through a bandwidth of several tens of gigabytes. The uncompressed data, which is larger than the compressed data, can be transmitted through a bandwidth of several tens of gigabytes. Uncompressed data is less vulnerable to packet loss occurring during data transmission than in the case of compressed data.
Data to be transmitted can be classified as data that must be immediately processed by a receiving station and data that does not need to be processed immediately by the receiving station. For example, the processing of video data and audio data may have priority over the processing of Internet data such as File Transfer Protocol (FTP) and Hypertext Transfer Protocol (HTTP) data.
Therefore, it is necessary to develop a technique of processing a plurality of data received by a receiving station according to priorities set among the plurality of data.